The pink mucket is classified as Vulnerable (VU) on the IUCN Red List (1).

The pink mucket (Lampsilis abrupta) is a freshwater mussel with a thick, rounded shell (2) (3) (4) (5). Males are slightly bigger in size, with a blunt posterior end to the shell (2) (3) (4). The outer shell is smooth and yellowish-brown in colour with darkly stained lines as a result of pauses in growth (2) (3). Faint green lines may be visible in juveniles, but are not usually seen in mature mussels (3) (5). The inner lining of the shell, called the nacre, is iridescent and white, often tinged with light pink towards the posterior end (2) (3) (4). Hinge teeth are used to keep the valves aligned and consist of both pseudocardinal and lateral teeth. Pseudocardinal teeth are structures found near the anterior-dorsal edge of the mussel while the lateral teeth are interlocking ridge-like structures which are found along the hinge of the mussel valves (6).The pink mucket has three well-developed, triangular pseudocardinal teeth, two in the left valve and one in the right (2). The lateral teeth are short and thick (3).

The pink mucket is found in the eastern United States and has historically been seen in disjunct populations from Oklahoma in the west to Virginia, and from Louisiana north to Illinois and Indiana (1) (4). Records from around 1900 indicate that there were only 16 known populations, and it is not certain where this species remains across its range (5).

The pink mucket favours large, fast-flowing rivers with gravel or sandy substrate, although it is able to survive in moderately flowing water (3) (4) (5) (7). It can be found in shallow water, to depths of one metre (3) (5) (7).

Like all mussels, the pink mucket is a filter feeder that is able to extract food particles from the water (4) (5) (7). Water is brought into the shell through siphons (4) (5) (7), and mucous in the mussel’s gills trap the nutrients as the water passes over them (3). The pink mucket feeds on plankton and detritus suspended in the water (3) (4). Excess water carrying unsuitable food particles is ejected through another siphon (3).

The reproductive cycle of the pink mucket is similar to that of other freshwater mussels in its range (5). Males release sperm into the water column, which is collected by the females through their siphon (3) (5) between August and September (7). The fertilised eggs are then held by the female pink muckets until the larvae, called glochidia, are fully developed (3) (5). Once the glochidia are released, usually between May and July (4), they must attach to a host fish to complete their development into mature mussels (3) (5) (7). The diet of glochidia consists of water and fish body fluids (5). Suitable host fish that have been identified are the largemouth bass (Micropterus salmoides), smallmouth bass (Micropterus dolomieu), spotted bass (Micropterus punctulatus) and walleye (Sander vitreus) (4) (5) (7). The female pink mucket is able to attract host fish close by thanks to a spotted mantle flap that is thought to mimic a fish eyespot (4) (5). This is possibly to increase the chance of glochidia attaching to a suitable host fish (4) (5). After around two to four weeks on the host fish, the tiny mature mussels drop off and, if they land in suitable substrate, will burrow into it and continue growing (3) (7). Pink muckets are known to live to 50 years of age (5).

Competition from the introduced zebra mussel (Dreissena polymorpha) poses a threat to the pink mucket, as does the illegal collection by humans and habitat modification or loss (3) (4).

Freshwater mussels were historically commercially harvested to make buttons using the shell (3). However, this practice is no longer considered a current threat to the pink mucket, although modern plastic buttons are often manufactured to resemble mussel shells (3).

Past threats to the pink mucket also include habitat modification, such as dredging and the straightening of rivers, as well as degradation of water quality (5).

The pink mucket is considered Endangered in many of the states in which it has been known to occur historically, including Illinois and Missouri (2) (5) (7). It is also listed as Endangered by the U.S. Fish and Wildlife Service (3).

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact: arkive@wildscreen.org.uk

Anterior: Situated at or near the front.

Detritus: litter formed from fragments of dead material.

Dorsal: Relating to the back or top side of an animal.

Fertilisation: the fusion of gametes (male and female reproductive cells) to produce an embryo, which grows into a new individual.

Larva: immature stage in an animal’s lifecycle, after it hatches from an egg and before it changes into the adult form. Larvae are typically very different in appearance to adults; they are able to feed and move around but are usually unable to reproduce.

Lateral: situated at or towards the sides.

Mantle: in molluscs, a fold of skin that encloses a space known as the mantle cavity, which contains the gills. The mantle is responsible for the secretion of the shell.

Plankton: aquatic organisms, usually tiny, that drift passively with water movements; includes phytoplankton (plants), zooplankton (animals), or other organisms such as bacteria.

Posterior: situated behind or at the rear.

Siphon: in molluscs, a tube-like structure through which water passes into or out of the mantle cavity.